Damage mechanisms, life prediction, and development of EB-PVD thermal barrier coatings for turbine airfoils

Thermal barrier coatings (TBCs) must successfully resist damage from a variety of environmental and mechanical mechanisms to be viable on turbine airfoils. This paper reviews engine-operative TBC damage mechanisms and the requirements for life methods that enable a designer and engine operator to achieve acceptable TBCed component lives. Understanding TBC damage mechanisms facilitates development of advanced TBCs. The following damage mechanisms are discussed:
• growth and cracking of the bond coating's thermally grown oxide and its interfaces
• molten deposit (sulfate salt and calcia–magnesia–alumina–silicate) wicking into TBC
• sintering shrinkage, particle impact, bond coating creep